Lamp grip socket



July 23, 1929. J. LoFGRx-:N

LAMP GRIP SOCKET Filed July 29. 1926 [NVE/v TOR doH/v LOFGREN Parental July 23, 1929.

UNITED STATES 1,721,566 PATENT OFFICE.

JOHN LOFGBEN, OF CHICAGO, ILLINOIS, ASSIGNOR TO RALCO MANUFACTURING COM- PANYLOF CHICAGO, ILLINOIS,

A CORPORATION OF ILLINOIS.

LAMP GRIP SOCKET.

Application led J'uly 29,

My invention relates to lamp sockets, especially of the type commonly referred to as grip socket-s for resisting or preventing accidental unscrewing of electric lamp bulbs. The object of the invention is to provide a lamp socket having such characteristics whereby it is especially adapted for use in places where the lamp and socket are subjected to unusual vibration as for exlo ample in factories or in locomotives and other vehicles. One of the specific objects of the invention is to provide a socket which will offer more resistance to the unscrewing than to the screwing-in of a lamp bulb., thus making it easy for a lamp vbase to be inserted but creating special resistance to the unscrewing thereof. Another object is to accomplish these purposes in a simple and inexpensive manner and to produce an inexpensive and durable article and one that can be used with present-day standard lamp bases.

I accomplish my objects by the mechanism illustrated in the accompanying drawings in which Figure 1 is an axial section of a lamp socket embodying my invention, the lamp base being shown in position. The section is taken on the line 1-1 Figure 2.

Figure 2 is a side elevation of the parts shown in Fig. 1, the view being taken at right angles to the plane of section of Figure 1.

Figure 3 is a top plan view of the lamp socket.

Figure 4 is a sectional view on the line 4 4 Figure 3.

Figure 5 is a top plan view of the shell of the socket showing the eccentricity of the gripping tongue.

Figure 6 is a side elevation of the shell showing the distorted position of the gripping tongue.

Like numerals denote like out the several views.

With regard to its general characteristics, my device is standard, having a base 10 which may consist of porcelain, fiber or other suitable insulating material, and may assume various configurations, depending upon the conditions under which it is to be used. It is provided with a center contact 12 which is equipped with binding screws 14 in the well-known manner. The strip portion parts through- 1926. Serial No. 125,703.

of this center contact is anchored to the base by a screw 16 or other appropriate means. Screws 17 are provided for securing the insulating base to any supporting structure. Mounted on the base is a shell 18 secured by means of screws 20 or equivalent devices. This shell is equipped with a contact strip 22 provided with binding screws 24. i

Now referring to the characteristics more intimately connected with the invention: the shell is internally threaded to cooperate with the thread upon the base 26 of an ordinary lamp bulb. The shell should be of metal somewhat thicker than ordinary sheet metal. For example, it may be constructed of brass tubing, the thickness whereof will vary somewhat with the size of th lamp to be accommodated. It should be heavy enough to maintain its form except when subjected to somewhat more than ordinary pressure.

In the form illustrated the shell has a slot 28 extending pait way in from the outer end of the shell and acommunicating slot 30 which extends part way around the shell cii'cumferentially. This results in the iformation of a portion 32 which is partially severed from the rest of the shell and for convenience may be referred to as a tongue.7 After the tongue is thus formed it is bent or distorted from its natural shape, and in the most developed form of my invention it is distorted in two different ways, viz lengthwise of the shell and also transversely. By distorting the tongue in a. lengthwise direction, that is, parallel to the axis of the socket, the threads of the tongue are distorted from the true helix and hence tend to create additional friction upon the threads of the lamp base. This friction is useful in resisting the accidental unscrewing of the lamp bulb due to vibration. In the preferred form the tongue is bent downward or inward toward the bottom of the socket, which eliminates any tendency of the tongue to catch on external objects.

The second distortion is radially inward as shown best in Figures 3 and 5. Thus the free end 33 of the tongue is closer to the central axis than the rest of the shell, the tongue itself being of approximately spiral form. This inward bending of the tongue performs two functions. First, it enables the device to accommodate itself to lamp bases which may vary slightlyin diameter. I claim as new and desire to secure by Let- 50 It will be understood that due to exigencies of 'manufacture lamp bases and sockets are not always of exact size, and by thus bending the tongue it enables the socket toaccommodate itself to bases of slightly dliermg diameters. Second, it increases the friction exerted upon the bulb. ,'Ihis is due to the additional pressure resultlng from the decreased diameter of the` tongue. g

According to the best construction the tongue extends in a negative direction circumferentially. By this I mean that it extends in the same direction which the lamp would rotate in being unscrewed. For the ordinary right-hand threaded lamp bulb the tongue extends in a counter-clockwlse direction when looking from the outer towards the inner end of the shell. The result of this formation of the tongue is that the tongue tends to wrap itself around the lamp base when the latter is unscrewed, the action being somewhat analogous to that of-a snub! ber. On the other hand when thev lamp base is being screwed into the socket the effect will be to push the tongue radially outward, thus decreasing the amount of friction.

As a result of my construction the lamp 4 bulb may be screwed into the socket perhaps with somewhat greater friction than with the ordinary socket due largely to the longitudinal distortion of the ftongue, but when -a tendency is exerted to unscrew the bulb it will be opposed both by the added friction due to the longitudinal distortion, and also to the snubbing elfect vgenerated by the tongue. Hence the lamp bulb may be relied on to maintain its position in the socket even-though subjected to unusual and excessive vibration such as is encountered in a railway locomotive.

It will be understood that the slotting may be varied somewhat froml the form shown, although the illustrated form is desirable. The ktongue need not be rectangular in outline, as illustrated, but Tnay be altered somewhat in outline without departing from the spirit of the invention.

Having thus described my invention what ters Patent is:

1. A'lamp socket having a threaded shell with a slot running lfrom the mouth part way inward and part way around the shell thus forming a partially severed portion, said partially severed portion being distorted lengthwise of the shell.

2. A lamp socket having a threaded shell with a slot running from the mouth part way inward and part way around the shell thus forming a partially severed portion, said partially severed portion being distorted with respect to its distance from the central axis of the shell for increasing the friction ona cooperating lamp base.

3. A lamp socket having a threaded shell with a slot running from the mouth part Way inward and part way around the shell thus forming a partially severed portion, said partially severed portion being distorted both lengthwise of the shell and also with respect to the central axis of the shell for the purpose of increasing the friction on a cooperating lamp base.

4. A lamp socket havinga threaded shell with a slot running from the mouth part way inward and part way around the shell in the positive direction thereby forming a tongue extending in the negative direction, said tongue being bent slightly inward toward its free end whereby it tends to wrap itself around the lamp base when the latter is unscrewed.

5. A lamp socket having a threaded shell with a Vslot running from the mouth part way inward and part way around the shell in the positive direction'thereby forming a tongue extending in the negative direction, said tongue being bent slightly inward toward its free end whereby it tends to wrap itself around the lamp base when the latter is unscrewed, said tongue being also distorted in the direction of the length of the socket for warping the thread and increasing the friction. l

In witness whereof, I have hereunto subscribed my name.

JOHN LOFGREN. 

